1. Technical Field
The present invention relates to a pick-up angle adjustment mechanism for optical disk apparatus.
2. Related Art
Conventionally, an optical disk apparatus such as an optical disk recording and reproducing apparatus is provided with a pick-up angle adjustment mechanism for adjusting the laser light emitted from an optical head so that the optical axis of the laser light becomes perpendicular to a recording surface of on optical disk.
FIG. 3 shows the configuration of a conventional pick-up angle adjustment mechanism for optical disk apparatus.
In FIG. 3, reference numeral 31 denotes a chassis; 32 denotes a spindle motor to rotate an optical disk; 33 denotes a turntable for mounting an optical disk; 34 denotes an optical pick-up; 35 denotes an optical head attached to the optical pick-up 34; 36 denotes a first guide shaft (A-shaft); and 37 denotes a second guide shaft (B-shaft). The optical pick-up 34 is connected to the A-shaft 36 and the B-shaft 37. By means of a drive means (not shown), the optical pick-up 34 is capable of reciprocating along the A-shaft 36 and the B-shaft 37 in the radial direction (R direction) of an optical disk.
A support member 38 supports an end A-1 of the A-shaft 36 toward the turntable 33 on the chassis 31. An adjustment member 39 supports the other end A-2. Adjustment members 40 and 41 are provided for both ends B-1 and B-2 of the B-shaft 37. The support member 38 supports the end A-1 of the A-shaft 36 to maintain a fixed height of the end A-1. The adjustment members 39 through 41 are used to adjust heights (a position perpendicular to the chassis 31) of the end A-2 of the A-shaft 36 and the ends B-1 and B-2 of the B-shaft 37. In this manner, a tilt of the optical pick-up 34 can be adjusted. It is possible to adjust a tilt angle (a tilt between the optical head's optical axis and the optical disk's recording surface) of the laser light radiated from the optical head 35.
Conventionally, there have been proposed various arrangements for the adjustment members 39 through 41.
For example, patent document 1 (Japanese Patent Application Laid-Open Publication 2003-187538) describes the guide shaft adjustment means composed of the adjustment plate, the elasticity means, and the adjustment screw as follows. The adjustment plate supports one end of the guide shaft and is rotatable around the other end in the direction approximately perpendicular to the optical disk surface. The elasticity means applies elasticity to the guide shaft and the adjustment plate in the direction approximately perpendicular to the optical disk surface. The adjustment screw is screwed into the adjustment plate. The tip of the adjustment screw touches the base to displace the guide shaft and the adjustment plate in the direction approximately perpendicular to the optical disk surface against the elasticity applied by the elasticity means.
Patent document 2 (Japanese Patent Application Laid-Open Publication 2002-170248) proposes the height adjustment mechanism provided with the adjustment screw that is threadably mounted on the spring and the chassis to support the guide shaft from the bottom. The spring presses to apply force to the end of the guide shaft from the top.
Patent document 3 (Japanese Patent Application Laid-Open Publication 2000-020962) proposes the height direction adjustment mechanism having the spring member and the locking member. The spring member always presses the end of the guide shaft upward in the direction orthogonal to the chassis. The locking member shows a T-shaped sectional view and has a disk portion that resists the spring member to prevent the end of the guide shaft from being raised over the chassis.
Patent document 4 (Japanese Patent Application Laid-Open Publication 10-143870) proposes the adjustment mechanism that is configured as follows. The adjustment screw is rotated to finely move horizontally and to vertically change the height of the guide shaft supported at the tapered portion of the adjustment screw.
Patent document 5 (Japanese Patent Application Laid-Open Publication 09-S20214) proposes the adjustment member using the cam as the bearing for the guide shaft.
Patent document 6 (Japanese Patent Application Laid-Open Publication 2001-344766) proposes the following adjustment mechanism. The adjustment mechanism uses the adjustment block having a long hole slanted at a specified angle. The end of the guide shaft is inserted into this long hole. The position of the adjustment block is moved to adjust the height of the guide shaft end.
Patent documents 7 (Japanese Patent Application Laid-Open Publication 10-064096) and 8 (Japanese Patent Application Laid-Open Publication 2002-288861) propose the position adjustment members using eccentric cams.
[Patent document 1] Japanese Patent Application Laid-Open Publication 2003-187538
[Patent document 2] Japanese Patent Application Laid-Open Publication 2002-170248
[Patent document 3] Japanese Patent Application Laid-Open Publication 2000-020962
[Patent document 4] Japanese Patent Application Laid-Open Publication 10-143870
[Patent document 5] Japanese Patent Application Laid-Open Publication 09-320214
[Patent document 6] Japanese Patent Application Laid-Open Publication 2001-344766
[Patent document 7] Japanese Patent Application Laid-Open Publication 10-064096
[Patent document 8] Japanese Patent Application Laid-Open Publication 2002-288861
Let us consider a case of using the position adjustment member to adjust slants of two guide shafts that guide and support the optical pick-up as mentioned above. When the same adjustment amount is applied to each position adjustment member, the respective ends of the respective guide shafts move at the same vertical distance. However, if the lengths of the guide shafts are different, angles and levels vary between the pair of the guide shafts, which might make difficult the angle adjustment work of the optical pick-up. In the prior art, the pair of the guide shafts have the same length for avoiding the difficulty and complicated adjustment work. The prior art requires shaft lengths to be the same, necessitating an unnecessary space.